Question

a(n) ______ can be defined as a substance that keeps ph within established limits by taking up excess h⁺ or oh⁻ in a solution.

multiple choice

○ acid
○ equalizer
○ buffer
○ solute
○ base

Explanation:

• An acid donates $H^+$ and lowers pH, not maintain it.
• "Equalizer" is not a scientific term for this function.
• A buffer consists of a weak acid and its conjugate base (or weak base and conjugate acid), which can absorb excess $H^+$ (by the base component) or $OH^-$ (by the acid component) to stabilize pH.
• A solute is a substance dissolved in a solution, not related to pH regulation.
• A base accepts $H^+$ and raises pH, not maintain it. So the correct answer is buffer.

Answer:

C. buffer